better cmake build

[hubutui]

Hey, it seems that the cmake way to build and install zopfli only install zopfli.h and zopflipng_lib.h to /usr/include/. Debian use Makefile to build, and manual install header files to /usr/include/zopfli:

libzopfli-dev: /usr/include/zopfli/blocksplitter.h
libzopfli-dev: /usr/include/zopfli/cache.h
libzopfli-dev: /usr/include/zopfli/deflate.h
libzopfli-dev: /usr/include/zopfli/gzip_container.h
libzopfli-dev: /usr/include/zopfli/hash.h
libzopfli-dev: /usr/include/zopfli/katajainen.h
libzopfli-dev: /usr/include/zopfli/lz77.h
libzopfli-dev: /usr/include/zopfli/squeeze.h
libzopfli-dev: /usr/include/zopfli/symbols.h
libzopfli-dev: /usr/include/zopfli/tree.h
libzopfli-dev: /usr/include/zopfli/util.h
libzopfli-dev: /usr/include/zopfli/zlib_container.h
libzopfli-dev: /usr/include/zopfli/zopfli.h

Are these header files part of zopfli? Should they be installed to system? Maybe the CMakeLists.txt needs to be updated.